Pulp yarn or twine



Patented Aug. 7, 1934 UNITED STATES PATENT OFFICE Company, Maine Berlin,

a corporation of No Drawing. Application November 4, 1931,

Serial No. 572,981

8 Claims. (Cl. 117-60) twisting into yarns or twines. Thus, the pulp' fibers may be deposited as continuous, spaced ribbons on a Fourdrinier wire and then progres- I 5 sively furled from edge toedge by a suitable roll engaging the edge portions of the ribbons while they are still in freshly-formed, wet condition and supported on the wire, as disclosed in application Serial No. 542,649, filed June 6, 1931, by

Milton 0. Schur and William B. Meglitz which has matured into Patent 1,910,407, May 23, 1933.

One of the faults with yarn so made from wood pulp is that its wet strength is considerably lower than its dry strength. By strength is meant the resistance to fracture or breakage when the yarn is subjected to tensile stresses. Thus, a yarn made from a typical high grade wood pulpof the nature of kraft may have a wet strength amounting to only about 80% of its dry strength, or

0 even less. The poorer wet strength of the yarn militates against its adoption in place of the usually more expensive yarn made on tensile machinery from cotton or other long-staple fiber. So, too, the factor of wet strength is of importance when the yarn is woven into coarse fabrics of the nature of burlap, gunny sacking, or the like, which enter into the making of bags or sacks for the storing and shipping of onions,v

potatoes, and other vegetables. In such case,

L0 since the filled bags are often exposed to the rain and may be hosed oif with water, it is desirable that the bagsbe possessed of a wet strength fully as good as their dry strength, in order to maintain their integrity under wet stress.

5 I have found that the wet strength of yarns or twines made from wood pulp as hereinbefore described may be greatly increased-in fact, increased to a point where the wet strength exceeds the dry strength,by the incorporation i of a relatively much longer-fibered. cellulose pulp of a different origin into the aqueous suspension of wood pulp used for depositing the pulp ribbons, which are furled into filaments for plying and twisting into yarns or strings. Va-

rious kinds of long-fibered pulps, for instance,

those prepared by completely pulping raw manila, sisal, ramie, hemp, and the like in chemical liquors, may be employed. For example, the long, coarse strands which constitute raw manila or sisal, may be resolved into a soft pu p composed of ultimate fiber units of approximately 3 to 5. mm. in length, by digestion under the proper conditions in alkaline liquors. The long-fibered pulp'may be cotton, rayon, or other fiber or combination of fibers.

While it is possible to incorporate various percentages of long-fibered pulp into.'the Wood pulp, one need not exceed about 50% long-fibered pulp in the mixture, for even with only this amount of long-fibered pulp in the yarn or string, it is found that the wet strength of the yarn has already been made to exceed its dry strength. The improvement can be seen from the following table, which shows the strength (both dry and wet) of an allwood pulp yarn of four plies and of a similar yarn made from a blend of similar wood pulp and an equal proportion of manila pulp:

The breaking length is a measure of tensile strength because it represents the length of yarn which, if freely suspended at one end, would break on account of its own weight. The yarn was tested for its wet tensile strength after it had been permitted to soak in water at room temperature for a five-minute period. The spectacular feature in the foregoing table is the vast difference in wet strength between the'all-wood pulp yarn and the yarn containing the manila pulp, although it is to be noted that the dry strength, too, is imprt'lrlwed appreciably by the presence of the manila I have also found that the foregoing improvemanila pulp, or has two different kinds of filaments, one kind consisting entirely of wood pulp and the other entirely of manila pulp. Thus, a

four-ply yarn similar to those classified in the I foregoing table but having two all-wood pulp filaments and two all-manila pulp filaments had the following characteristics:

Dry breaking Wet breaking Twlst length (yds.) length (yds.)

It is, of course, possible to increase the percentage of long-fibered pulp to the point where the yarn consists entirely of long-fibered pulp, in which case one would maximize the strength (both dry and wet) of the yarn. On the other hand, one need not use more long-fibered pulp than that necessary practically to equalize both the wet and dry strengths of the yarn. One of the interesting 1. As an article of manufacture, yarn or twine having a wet strength at least substantially equal to its dry strength and consisting of waterlaid.

ribbons of pulp furled from edge to edgeto filamentary form and intertwisted, at least a portion of said pulp being much longer-fibered than wood pulp.

having'a wet strength at least substantially 'equal to its dry strength and consisting of waterlaid ribbons of pulp furled from edge to edge to filamentary form and intertwisted, said ribbons being made up of wood pulp and a longer-fibered pulp of different origin.-

3. As an article of manufacture, yarn or twine having a wet strength at least substantially equal 2. As an article of manufacture, yarn ortwine' -rived from a different source.

5. As an article of manufacture, yarn or twine having a wet strength at least substantially equal 91 to its dry strength and consisting of waterlaid ribbons of pulp furled from edge to edge into filaments and intertwisted, some of said filaments being composed ofwood pulp and others being composed of a longer-fibered cellulose pulp derived from a different source, all of said filaments being treated with the same dye but presenting different colors or depths of color.

6. As an article of manufacture, yarn or twine having a wet strength at least substantially equal 106 to its my strength and consisting of waterlaid ribbons of pulp furled from edge to edge to filamentary form and intertwisted, said ribbons being made up of a mixture of wood pulp and manila pulp.

7. As an article of manufacture, yarn or twine having a wet strength at least substantially equal to its dry strength and consisting of waterlaid ribbons of pulp furled from edge to edge to filamentary form and intertwisted, said ribbons being 110 made up of a mixture of substantially equal proportions of wood pulp and manila pulp.

8. As an article of manufacture yarn or twine having a wet strength at least substantially equal to its dry strength and consisting of. waterlaid ribbons of pulp furled from edge to edge-into filaments and intertwisted, some of said filaments being composed of woodpulp and others being composed of manila pulp.

GEORGE A. RICHTER. 

